Scientists tracking Happy Feet, the wayward penguin who became a worldwide celebrity after washing up on a New Zealand beach, fear he may have been eaten by predators.

Researchers said they had received no transmissions since last Friday from a satellite tracking device attached to the penguin after he was released into the icy Southern Ocean on September 4.

Happy Feet may have been eaten by predators or the tracking transmitter may have failed or fallen off as he swam in the sub-Antarctic waters where a New Zealand research vessel dropped him off, researchers said.

Colin Miskelly, from Wellington's Te Papa museum, who advised on Happy Feet's two-month rehabilitation after he was found emaciated and near death on a New Zealand beach in late June.

He says efforts will continue to relocate the bird.

"He was tracked for another five days after release and during that time he'd travelled over 500 kilometres in a south-easterly direction. And then on Friday morning was when the last signal was received," he said.

"And for a while over the weekend we were wondering if there was some sort of technical glitch and there was speculation that solar flares were interrupting satellite transitions.

"But it's now pretty clear that there have been no transmissions from the transmitter since Friday morning.

"Whether that is because of some sort of malfunction, like if the transmitter fell off for example and it was in deep water it wouldn't transmit, or whether he's inside the belly of a predator, we've got no way of knowing."

Researchers would not expect to receive transmissions from the satellite tracker if Happy Feet had been eaten by a larger predator.

But Mr Miskelly says Happy Feet could still be alive and he may even once again appear unexpectedly.

"I suppose from the penguin's perspective the best-case scenario is that the transmitter's either failed or fallen off," he said.

"We're probably never going to know, but there is a slight caveat to that is that he's still carrying a transponder, which is like a microchip you'd put in a dog.

"So that's been inserted in the skin over the thigh. And so if he ever turns up at a monitored colony or if ever turned up on a beach near where people are and was able to be scanned, then that would show that that's him come back.

"So it's not impossible that he'll turn up somewhere in future and remind us all that he's not just another penguin."

If he is alive, the three-year-old Happy Feet has time on his side. Emperor Penguins live for around 20 years, more than enough time to check in.